In water softener systems, multiple tanks provide an efficient and reliable means of providing continuous soft water. In single tank systems, a reserve capacity is often configured into the tank controller. The reserve capacity helps to ensure that hard water is not delivered (i.e., to ensure untreated water is not output) during periods of normal water usage until a regeneration can be performed. For example, if regeneration is configured to occur at 2:00 a.m., and non-reserved softening capacity becomes exhausted at 10:00 a.m., the reserve capacity can maintain soft water production until the scheduled regeneration time. Any reserve capacity not exhausted will be regenerated, thereby lowering the efficiency of the system.